Rotary hook



Patented Oct.. 26, 1948 ROTARY HOOK George R. Wainwright, Glendale,Calif., assignor, by mesne assignments, to William H. Maxwell,

Los Angeles, Calif.

Application October 2, 1944, Serial No. 556,723

8 Claims.

This invention has to do with a rotary hook of a sewing mechanism, thatis, with an assembly of elements for handling a bobbin in a lock stitchtype sewing machine, and it is a general object of the invention toprovide improvements in the mounting of a bobbin case base in a hookunit and an improved arrangement and relationship of hook unit, bobbincase base and thread guard.

Sewing mechanisms or bobbin handling mechanisrns employed in lock stitchtype sewing machines involve essentially a hook unit, a bobbin casebase, a bobbin case carried by the base and in turn supporting thebobbin proper, and a thread guard. It is advantageous in practice tosupport the bobbin case base in the hook unit so that there is a certainamount of freedom of movement between these elements and it is alsodesirable to have the thread guard supported so that it is rigid withthe hook unit.

It is a general object of my present invention to provide a structure ofthe general character hereinabove referred to wherein the bobbin casebase is yieldingly supported in the hook unit so that there is a certainlimited clearance or freedom of movement between these parts that willfree foreign matter that might otherwise tend to jam the mechanism orinterfere with free operation.

It is another object of this invention to provide a mechanism of thegeneral character referred to having a yieldingly supported bobbin casebase in combination with a thread guard which is rigidly supported fromthe hook unit. With the construction that I have provided the hook unitsupports or forms a base for both the bobbin case base and the threadguard, but the bobbin case base and thread guard are mounted on the hookunit to be entirely independent of each other.

Another object of the present invention is to provide a simplified andimproved yielding support for a bobbin case base. The structure of thepresent invention involves a single spring element which yieldinglyretains the bobbin case base in place in connection with the hook unit,this single spring being the only part or element that moves or operatesto allow shifting of the bobbin case base relative to the hook unit. Byemploying a single spring element I obtain a uniform action which isdiiiicult, if not impostion will be fully understood from the followingi' detailed description of a typical preferred lform and application ofthe invention, throughout which description reference is made to theaccompanying drawings, in which:

Fig. 1 is a side elevation of a mechanism provided by my presentinvetion. Fig. 2 is a face or front view of the mechanism shown in Fig.l. Fig. 3 is a sectional View taken as indicated by line 3 3 on Fig. 2.Fig. 4 is a transverse sectional view being a View taken substantiallyas indicated by line 4 4 on Fig. 3. Fig. 5 is an enlarged detailedsectional View showing marginal or flange portions of the hookand thebobbin case base at a point to show the mounting of the guard from thehook unit. Fig. 6 is an enlarged detailed sectional view showingmarginal or flange portions ofthe hook unit and bobbin case base at apoint to show the manner in which these parts are connected and Fig. '7is an enlarged detailed sectional View of the connection shown i'n Fig.6 taken at the screw shown therein and in a direction normal to theplane of Fig. 6. v

The mechanism in which my present invention is incorporated involves,generally, a hook unit A, a bobbin case base B, a bobbin case C, abobbin D, means E yieldingly retaining the bobbin case base in the hookunit and a thread guardF supported from the hook unit independently` ofthe bobbin case base and the means EL .These various essential elementsare normally assembled together as a unit or mechanism to be carried onthe end of a shaft, the bobbincase base being supported in the hookunit, the bobbin case being supported in the bobbin case base B and thebobbin in turn being supported in the case C. The means E serves toyieldingly retain the base B in the hook unit A while the guard F issupported directly on the hook unit A to surround the projecting portionof the bobbin case base without in any way contacting it or interferingwith its movement or action.

Since my present invention is primarily concerned with the mounting ofthe bobbin case base B in the hook unit A through the means E and withthe thread guard F and the-manner in which it is mounted on or supportedfrom the hook unit A in relation to the bobbin case base B, I willconfine my description largely to these parts or features of theconstruction and will only make general reference to other structuralfeatures of the ymechanism which may, in practice, be features such asare common to' or conventional i mechanisms of this kind.

The hook unit A is the basic part ofthe mechanism and is the member orelement by which the mechanism is supported from an operating shaft. Inthe preferred form, as shown in the drawings, the hook unit involves,generally, a forwardly opening or facing cup-like body I and a mountinghub II. The body I8 includes an inner end wall I2 which projectsradially from the forward end of the'hub II and a peripheral side wall'I3 which projects forward from the outer edge portion or margin of theend I2. The hub Il projects rearwardly from the end I2 and is providedwith a central bore I4 to receive an operating shaft and has a tappedopening I5 to carry a set screw for securing the mechanism on a shaft.In addition to the parts thus far described the hook unit includes or isprovided with a ange I 6 which projects radially from the rim 'orforward end of the side wall I3, which dange is finished to have a flatsmooth forward front face I1. parts ofthe hook unit kare tformedintegrally, that isgthey are formed 'as a singlepontinu'ous integralunit, 'as shown throughout the drawings.

The bobbin case' base B isi a cup-liller element supported partiallyinthe hook unit Ato be concentric therewith and to face forward or inthe same direction asthe hook unit. i In its preferred form the bobbincase base involves, generally, an inner end I8, an annular side wall I9projecting forward from the peripheral edge or margin of I the end wallI8, and a mounting flange projecting radially from the side wall I9.TheI flange 2B of the bobbin'c'ase base is located about midway betweenthe two ends of 'this unit, that is, itis located to project from themiddle portion of the side wall I9 and it is lprovided to support thebobbin case base B in or from the hook unit A so that there is a threadpassage or channel 2'Iv between these unitsor elements of the mechanism,as lclearly shown in Fig. 3 of the drawings. f

' The bobbin case base B facing downwardly, as above described, forms areceptacle or carrier that receives the Ybobbin case' CY in which thebobbin D is mounted. `The bobbin case C includes, generally, aforwardend or flange 22 and 'a rearwardly extending side wall 23 proportionedto Vfit into 4the opening or cavity of the bobbin casebase. The bobbin Dis arranged within the case C on a central hub 24 provided in the case'so that it is confined between 4the wall I8 of the bobbin case base and'the'wall 2,2 f the bobbin case. Inthe drawings Imhave'shown'a centralspindle 25 in the bobbin'case base entering the hub 24 of the bobbincase 'fand in practice any suitable means or mechanism may beincorporated in the structurefor retainingthe parts just described intheproper assembled relationship.

In accordance with the construction that I have provided a recess orchannel is provided in the corner formed where the sidewall I3 andflange I6 of the hook unitljoin. This channel 3l] is formed concentricwith 4the axis of the 'mechanism and is shaped and proportioned toreceive or accommodate the flange 2B of the bobbin case base. The radialextent of the channel is suchas to v receive the flange 20 with workingclearance and the depth ori axial extent of the channel'is madesubstantially equal to the thickness of the flange 20 so that when thebobbin case clase is in thev normal'fposition in the hook u'nitAftheouter side 3l of the 'flange 20 lies in the same plane as the outer sideor face I'I of thenange 16 ofthe hook unit A. The means E In thepreferred construction the several L which I have provided for retainingthe bobbin case base B in the hook unit A or in other words forretaining the flange 20 in the channel 30 involves a single spring. Thisspring is a flat or leaf spring arcuate in form, being formed on acenter concentric with that of the flange I6 and extending aroundthrough an angle of substantially 280. YThe main portion or body 4I] ofthe leaf spring is proportioned so that it is substantially as wide asthe face I1 of the flange I6 between the channel 30 and the outer edge4I of the flange.

The spring is secured or made fast to the face I1 of the flange I6 atspaced points, preferably at two spaced points as I have shown in thedrawings, this being sufcient to hold the spring in place and to gainthe action desired as hereinafter described. In the drawings I haveshown the spring fastened to the face I1 at two spaced points by meansof screws 43 which pass through openings 4d in the spring and threadinto tapped openings 45 in the flange, the heads 45 of the screws beingengaged over the spring to clamp the spring to the face I1 of theflange.' Where the spring is arcuate, as I have described, and extendsthrough about 280 I can advantageously locate the screws or points offastening about 65n from the ends of the spring so that they occur about126 apart. It is to be noted that the spring is mounted -through thescrews 43so that the gap or opening between its` two ends occursopposite or in register with the thread handling parts of the mechanismor, in other words, at the thread channel which enters the hook unit Aso that the spring in no way interferes with the threadhandling actionof the mechanism.

` In accordance with ymy invention I provide inwardly projecting lips'41on 4the spring to overhang or overlie the outer side V3l ofthe flange2001 the bobbin case base. The lips serve to retain the flange 20 in thegroove 30 and they are proportioned and locatedon the bod7 IIB of thespring so that they retain `the flange 2IJ'in' the groovel 38 with lthedesired resilience. Where the spring is arcuate and proportioned aboutas I-have described and `where it is 'fastened at two points, as by twoscrews 43 as I h'ave`described, I find it practical to provide one lip4I on the inner edge of the spring between the two 'screws and lipsoutward of the screws and extending to the ends of the spring. With thisarrangement I have three spring lips 4'! retaining the flange 2G in thechannel 30 and these lips are spaced around the flange so that theretention is substantially uniform. In practice I may make the spring 4Bflat `or I may crimp or corrugate it slightly at each side 0f each screwto give it added resilience orflexibility. lCrimps or bends I8 such as Ihave just referred to are shown in Fig. 7 of the drawings. I

The thread guard F extends around the front or forward kend portion ofthe mechanism thus far described, so that itis located in front of theassembled flanges i5 and 20 surrounding the forwardly projecting portionof the bobbin case base B. In the particular form of constructionillustrated theV guard, as shown in Fig. 2, is fiat and correspondsgenerally in size and shape to the flange I6 of the hook unit and has anopening EU sufficiently large to pass the forward or projecting portionof the bobbin case base with clearance. VIn accordance with my inventionI support the thread guard F from the ange I6 of the hook unit andIpreferably provide a plurality of points of support -for the guard sothat the guard'is supported firmly in spaced relation immediatelyforward of or in front of the assembly of the flanges l5 and 2D and thespring of means E.

In the preferred construction I provide three points of support for thethread guard and each of these supports involves a screw 6| carried inan opening 62 in the flange I6 of the hook unit and threaded in anopening 63 in the guard and a spacer in the form of a collar 64surrounding the screw and bearing between the face Il of the flange i6and the inner side of the thread guard. The spacer is proportioned tospace the thread guard away from the spring of the means E so that thereis the desired clearance between these parts, as shown throughout thedrawings. The spacers may be separate from the guard or they may bevfastened or joined thereto, in which case they may be threaded so thatthe screws 6| thread into them, as well as into the guard, as shown inthe drawings. The screws 6l enter the openings 62 from the rear face ofthe ange and their heads 6l are preferably countersunk'into the flange,as shown in the drawings.

In accordance With my invention the mount- X ing of the thread guardfrom the flange I6 is entirely independent of the support or retentionof the flange 2U in the channel (itl. In order to prevent interferencebetween these various elements I provide the spring of the means E withopenings 10 which pass the guard supports with clearance, that is`openings suiciently large to pass the spaceres 64 with suitableclearance, as clearly shown in Fig. 5 of the drawings. Where I providethree supports for the thread guard, as shown in the drawings, I locateone midway betweenthe two screws 43 and one at or near each outer end ofthe spring of means E. This gives the thread guard support at threepoints about equally spaced around the structure which, in practice, isample.

In addition to the parts thus far described the mechanism may includefeatures or elements common to this class of mechanism, for instance, atthe desired point around the flange l5 it may be fashioned to present aforwardly facing thread engaging tongue 8@ and immediately forward ofthe tongue in the direction of rotation of the mechanism, the hook unithas an inwardly and rearwardly extending thread passing notch or channel8l. Further, the thread guard at its inner edge portion may be cut awayat 32 and formed to leave a forwardly projecting offset thread engagingtongue 83 which overlies and registers with the tongue 80 of the hookunit and projects from the guard to catch the thread. I'hese variousparts may be proportioned or fashioned in the manner common to mechanismof this kind so that they serve or function in the manner common tomechanisms of this character. In like manner the mechanism may include arecessed tongue Si] projecting from the bobbin case base B and a tongue9i projecting from the bobbin case to cooperate with the tongue 98 and athread tensioning spring member 92 may be provided in connection withthe tongues. In practice these elements can be varied as circumstancesrequire, as my invention is in no way concerned with them but isconfined to the features and combinations of construction which I haveindicated.

From the foregoing description it will be apparent that I have provideda construction whereby the bobbin case base B is effectively anddependably supported in the hook unit A to cui operate vmost effectivelyand'yetf lit is yieldingly. held or supported softhat it willwfree vorclear foreign matter that would otherwise tend to jam' the mechanism..,Likewise, it will be apparent that Ihave provided a construction ofthe general character referred to having a thread guard of a mostadvantageous type or form guardingthe structure by which the bobbin caseis retainedin the hook unit and that this.,.thread guard is mounted sothatit `is in adenite .predetermined position relative tothehookunit andis-entirely independent-:of.theumounting of the bobbin case base in thehook unit. The thread guardpresents a smooth surface overy whichthe-thread rolls or slides while being passed aroundfthe bobbin case andprovides a guard for the means With thc construction vthat I haveprovided -I have minimized danger of improper operation due to minormisalignment `of parts. Forv instance. should there be` aslightmisalignment crimperfection in the thread guard it will not `inany way interfere with or'disturb the proper ,action or functioning ofthe 'bobbincase base and `likewise the bobbin case base is free tofunction and may clear itself of foreign matter without in any Wayinterfering with or putting strain upon the thread guard.

It is also to be noted that I have provided a construction whereby theseveral screws involved can be mounted or set tight to eliminate dangerof working loose without danger of binding or setting any of the partsso that their Voperation is impaired.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in the art and fallwithin the scope of the following claims.

Having described my invention, I claim:

1. In a mechanism of the character described, a cup-like hook unit, abobbin case base supported in the said unit, and a single leaf springyieldr ingly retaining the said base in the said unit, the

spring being attached to the unit and having circumferentially spacedlip parts projecting from its inner edge yieldingly engaging the base.

2. In a mechanism of the character described, a hook unit, a bdbbin casebase supported in the unit, means yieldingly retaining the base in theunit, and a thread guard supported on the unit at the front of the unitopposite said means and l independent of the said means.

3. In a mechanism of the character described, a hook unit having aflange at its forward end, a bobbin case base supported in the unit atthe flange, means carried by the flange yieldingly retaining the base inthe unit, and a thread guard supported at the forward end of the unitand from the flange independent of said means.

4. In a mechanism of the character described, a hook unit having aflange at its forward end, a bobbin case base supported in the unit atthe ange, a leaf spring carried by fthe flange yieldingly retaining thebase in the unit, and a thread guard supported at the forward end of theunit and from the ange independent of the said leaf sprlng.

5. In a mechanism of the character described, a hook unit having a angeat its forward end, a bobbin case base supported in the unit at theflange, a leaf spring carried by the flange yieldingly retaining thebase in the unit, a Ithread guard at the forward end of the unit free ofthe base,

attuare? andfsp'aoedsupports mounting the guard Yfrom the flange'independent cf the? spring.

6;, In a mechanism of the charaote'r'descri-bed, a :liable-unitV having`a. flange at its forward end, a-bobbin'case base supported intheunit-.at the flange,` a leaf spring carried by the' flangeyieldinglyrretaining the. base in the unit, screws xing the spring tothe an'ge at spaced points, a thread guard at the'iorward Vend of theunit free of the 'basegandr spaced supports mounting the guard from: theiiange independent of the spring.

7.: In fa" mechanism of the character described, fa hook `unit having aflange at itsforward end, a bobbin case base supported in the' unit atthe tlangefa leaf spring vcarried by the ange yieldingiy retaining thebase in the unit, a thread guardfat' the forward end of theunit free ofthe base,and-spaced supports mounting fthe guard from the flangeindependent of the spring, the spring' having openings passing the saidsupports with/clearance.

8. In a mechanism of the character described, a. hook-unit-having aflange at its forward encl,v a

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,065,349 Southam et al; Dec. 22,1936 FOREIGN PATENTS Number Country Date 493,915 Germany Mar. 17, 1930

